Configuring a Mirror Virtual IP (VIP)

To ensure that the management portal and Studio can seamlessly access the mirror regardless of which failover member is currently the primary, it is recommended that the failover members be configured to use the same superserver and web server port numbers.

ECP application servers do not use a mirror’s VIP. When adding a mirror as an ECP data server (see Configuring ECP Connections to a Mirror), do not enter the virtual IP address (VIP) of the mirror, but rather the DNS name or IP address of the current primary failover member. Because the application server regularly collects updated information about the mirror from the specified host, it automatically detects a failover and switches to the new primary failover member. For this reason, both failover members and any DR async members must be configured as ECP data servers with the same Maximum number of application servers setting. See Configuring ECP Connections to a Mirror for further ECP considerations.

When configuring one or both failover members as license servers, as described in the “Managing Caché Licensing” chapter of the Caché System Administration Guide, specify the actual hostname or IP address of the system you are configuring as the Hostname/IP Address; do not enter the VIP address.

To configure a mirror VIP, you must enter the following information:

• An available IP address to be used as the mirror VIP. It is important to reserve the VIP so that other systems cannot use it; for example, in a Dynamic Host Configuration Protocol (DHCP) network configuration, the VIP should be reserved and removed from the DNS tables so that it is not allocated dynamically to a host joining the network.

• An appropriate network mask, which you must specify in Classless Inter-Domain Routing (CIDR) notation. The format for CIDR notation isip_address/CIDR_mask, where ip_address is the base IP address of system, and CIDR_mask is platform-dependent, as follows:

  • Mac OS X — must be /32.

  • All other platforms — must match the mask of the IP address assigned to the base interface. For example:

    bash-2.05b# uname -a 
    AIX apis 3 5 00C0B33E4C00
    bash-2.05b# ifconfig en1
    en1:
    flags=5e080863,c0<UP,BROADCAST,NOTRAILERS,RUNNING,SIMPLEX,MULTICAST,
    GROUPRT,64BIT,CHECKSUM_OFFLOAD(ACTIVE),PSEG,LARGESEND,CHAIN>
            inet 10.0.2.11 netmask 0xffffff00 broadcast 10.0.2.255
            tcp_sendspace 131072 tcp_recvspace 65536 rfc1323 
    
    

    

    In this example, the en1 interface has a base address of 10.0.2.11 with a netmask of 0xffffff00, which translates to /24. Therefore, to assign 10.0.2.100 as the VIP to the en1 interface, you specify the network mask as follows (in CIDR notation): 10.0.2.100/24.

• An available network interface on each of the failover members. The interfaces selected on the two systems must be on the same subnet as the VIP.

  When selecting a network interface, the following platform-specific rules must be followed to ensure correct behavior:

  • IBM AIX®, Linux (Red Hat and SuSE), Apple Mac OS X, and Windows — An existing physical network interface must be provided during VIP configuration. On these platforms, IP address aliasing is used to bind an IP address (that is, the VIP) to an existing physical network interface. This platform allows a single physical network interface to host multiple IP addresses.